1. Field of the Invention
The present invention relates to a combination viscosity measuring device and stirrer, and in particular to such a device for measuring the viscosity and stirring fluid which is subsequently to be pumped and atomized in an airless sprayer.
2. Description of the Prior Art
Several types of devices are known in the art for measuring the viscosity of a fluid by measuring different properties of the fluid. A viscosity cup, for example, is described in U.S. Pat. No. 2,633,778 which measures the molecular shear forces within the fluid in which it is placed. Other types of devices measure the surface cohesion of the fluid by measuring the ability of the fluid to span an opening. Such a device is described, for example, in U.S. Pat. No. 4,228,678 wherein a disk having a plurality of spaced circular apertures of different diameters is rotated within a container holding a fluid whose viscosity is to be measured.
Another type of surface tension meter is disclosed in U.S. Pat. No. 2,710,539 which has a plurality of linearly disposed successive rings of varying diameters, the device being dipped into and removed from a liquid whose viscosity is to be measured with the largest ring opening which is covered by a film of the liquid being a measure of the viscosity of the liquid.
Another viscosity measuring device which measures surface tension or cohesion of the fluid is described in German Pat. No. 466,653. This device also has a plurality of linearly disposed circular apertures and is dipped into a liquid and removed therefrom thus leaving a thin web of fluid across a certain number of the apertures, the greater the degree of surface tension in the fluid, the larger the aperture which the fluid will span. The device disclosed in German Pat. No. 466,653 additionally is tapered so that a number of apertures having the same diameter, but different thicknesses, are also provided.
A problem exists in the painting technology in the use of airless sprayer units to apply fluid such as paint to a surface. Depending upon the design of the sprayer, the nature of the paint, and the coverage desired, proper viscosity of the paint which is supplied to the sprayer for pumping and atomization is important. Many applications may require the paint to be thinned before use with a particular sprayer.